This application claims the priority benefit of Taiwan application serial no. 90103359, filed Feb. 15, 2001.
1. Field of the Invention
The invention relates in general to a post metal etch cleaning method. More particularly, this invention relates to a one-solvent wet cleaning approach to clean a metal line after being patterned and etched.
2. Description of the Related Art
In the conventional method for patterning or defining a metal line, a patterned photoresist layer is typically formed on a metal layer with a portion of the metal layer exposed. The exposed metal layer is then removed using the photoresist layer as a mask. The photoresist layer is then removed to complete the pattern of the metal line.
However, for the aluminum (Al) or aluminum-copper (Alxe2x80x94Cu) alloy metal layer, the etching gas to remove the metal layer normally contains oxygen that will be reacted with the photoresist layer to form polymer residue on sidewall of the metal line. Therefore, a post cleaning step is usually performed after patterning the metal line to remove the polymer residue.
In the conventional post metal etch cleaning method, a hydroxyamine based (NH2OH) solvent is used to clean the metal line. A 1-mephyl-2-pyrrolidinone (NMP) solvent is further used as the intermediate solvent to clean the metal line. A de-ionized water is then used to rinse the metal line, followed by evaporating the de-ionized water with iso-propyl alcohol (IPA) to dry the metal line.
In the method described above, when the hydroxyamine based solvent reacts with water, the reaction produces a OHxe2x88x92 free radical which can easily react with Al or Alxe2x80x94Cu alloy to cause corrosion or galvanic reaction of the metal line. However, if one tried to adjust the composition or condition of the hydroxyamine based solvent in order to resolve the corrosion or the galvanic reaction problem, it is very likely that the polymer residue cannot be cleaned or removed thoroughly.
In addition, the intermediate solvent, that is, the NNW solvent, used in the above conventional method is to replace the amine based solvent which may destroy the hydroxyl contained in the de-ionized water and attack Al or Alxe2x80x94Cu. However, to adjust the proportion of such solvent in order to remove the polymer residue thoroughly without damaging the metal line is very difficult.
The invention provides a post metal etch cleaning method. An Al or Alxe2x80x94Cu metal layer is formed. A photoresist layer is formed on the metal layer, and a portion of the metal layer is exposed. The exposed metal layer is etched away. The photoresist layer is removed. A fluorine-based organic acid solvent is used to rinse the metal layer, followed by removing the fluorine-based organic acid solvent by a physical method. The metal layer is then flushed with a de-ionized water which is later evaporated off in a drying step, so as to dry the metal layer.
The invention also provides a post metal etch cleaning method and its application to the fabrication method for the metal line. The method begins by providing a substrate with a metal layer formed thereon. A photoresist layer is then formed on the substrate, so that a portion of the metal layer is exposed. The exposed metal layer is etched away. The photoresist layer is removed. A fluorine-based organic acid solvent is used to rinse the metal layer, followed by spinning off the fluorine-based organic acid solvent by a physical method. The metal layer is then flushed with de-ionized water which is later removed in a drying step, so as to dry the metal layer.
By the method provided in the invention, the polymer residue formed on the metal line can be removed effectively without damaging the metal line. In addition, the process window can be widened, the cleaning efficiency is enhanced while the metal corrosion or galvanic reaction is prevented. Furthermore, the consumption of the solvent is reduced to lower the fabrication cost, and the throughput is thus greatly improved.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.